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Statement - 1 : When ultraviolet light i...

Statement - 1 : When ultraviolet light is incident on a photocell , its stopping potential is `V_(0)` and the maximum kinetic energy of the photoelectrons is `K_(max)` when the ultraviolet light is replaces by X- rays both `V_(0) and K_(max)`increase
Statement - 2 : Photoelectrons are emitted with speeds ranging from zero to a maximum value became of the range of frequencies present in the incident light

A

Statement-1 is true, Statement-2 is true, Statement-2 is the correct explanation of Statement-1.

B

Statement-1 is true, Statement-2 is true, Statement-2 is not the correct explanation of Statement-1.

C

Statement-1 is false, Statement-2 is true.

D

Statement-1 is true, Statement-2 is false.

Text Solution

AI Generated Solution

The correct Answer is:
To solve the question, we need to analyze both statements provided and understand the principles of the photoelectric effect. ### Step-by-Step Solution: 1. **Understanding Statement 1**: - The statement mentions that when ultraviolet light is incident on a photocell, the stopping potential is \( V_0 \) and the maximum kinetic energy of the photoelectrons is \( K_{max} \). - When this ultraviolet light is replaced by X-rays, both \( V_0 \) and \( K_{max} \) increase. 2. **Analyzing the Photoelectric Effect**: - According to Einstein's photoelectric equation: \[ E = \frac{hc}{\lambda} = \phi + K_{max} \] where \( E \) is the energy of the incident photons, \( \phi \) is the work function of the metal, and \( K_{max} \) is the maximum kinetic energy of the emitted photoelectrons. - When the wavelength decreases (as it does when moving from ultraviolet to X-rays), the energy \( E \) increases. 3. **Effect of Increasing Energy**: - Since the work function \( \phi \) is constant for a given metal, an increase in the incident photon energy \( E \) results in an increase in \( K_{max} \): \[ K_{max} = E - \phi \] - Consequently, if \( K_{max} \) increases, then the stopping potential \( V_0 \) also increases, since: \[ K_{max} = eV_0 \] - Therefore, both \( V_0 \) and \( K_{max} \) increase when ultraviolet light is replaced by X-rays. 4. **Conclusion for Statement 1**: - Statement 1 is **True**. 5. **Understanding Statement 2**: - The statement claims that photoelectrons are emitted with speeds ranging from zero to a maximum value because of the range of frequencies present in the incident light. - In the context of the photoelectric effect, if the light has a single frequency, the emitted electrons will have a maximum kinetic energy determined by that frequency. 6. **Analyzing the Range of Speeds**: - The range of speeds (or kinetic energies) of emitted photoelectrons does not arise from a range of frequencies, but rather from the varying energy losses due to collisions within the material. - If an electron experiences collisions, it may lose kinetic energy, resulting in a speed less than the maximum. Thus, the maximum speed corresponds to electrons that do not lose energy through collisions. 7. **Conclusion for Statement 2**: - Statement 2 is **False**. ### Final Verdict: - Statement 1 is True, and Statement 2 is False.
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